1. Field of the Invention
The present invention relates to power tools. Specifically, it relates to techniques for preventing, as far as possible, an object other than a work from making contact with a rotating tool.
2. Description of the Related Art
U.S. unexamined patent application No. 17336/2002 sets forth a power tool that performs an emergency stop of the tool's rotation when an operator's hand has made contact with the rotating tool. This power tool utilizes the difference of the electric conductivity between human beings and work (wood). The electric potential of the rotating tool becomes higher when the operator's hand makes contact with the rotating tool than the electric potential of the rotating tool when the work (wood) makes contact with the rotating tool. Using this potential difference, the power tool detects timing when the operator's hand makes contact with the rotating tool. The power tool performs an emergency stop of the tool's rotation when the electric potential of the rotating tool becomes higher than a predetermined level. Alternatively, the rotating tool is caused to rapidly retreat to a safe zone.